﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


namespace ConsoleApp3
{
    class Stringutil
    {
        public static void Anull()
        {
       Boolean falg;
            Console.WriteLine("请输入：");
       string a = Console.ReadLine();
            if (string.IsNullOrWhiteSpace(a))
            {
                falg = true;
            }
            else
            {
                falg = false;
            }
    }

